A conventionally-known reaction force generating apparatus is configured to apply a reaction force to a rotation member which is subjected to a load, and one example of the reaction force generating apparatus is disclosed in International Publication No. 2013/099581. The reaction force generating apparatus disclosed in International Publication No. 2013/099581 applies a reaction force in a returning direction of a pedal member to the pedal member which is stepped on by a driver. The reaction force generating apparatus has: an arm through which the load is transmitted from the pedal member; a transmission member for rotatably supporting the arm; and a motor for applying a torque serving as a “reaction force” to the transmission member. Furthermore, the reaction force generating apparatus disclosed in International Publication No. 2013/099581 has first to third deceleration sections installed along a transmission passage from the motor to the transmission member.
The reaction force generating apparatus comprises: a pinion gear which is coupled to the rotor of a motor; and a first gear which is rotatably supported by a first support shaft. The pinion gear is meshed with the first gear. The pinion gear and the first gear correspond to the first deceleration section. The reaction force generating apparatus further comprises: a second gear which is integrally rotated with the first gear; and a third gear which is rotatably supported by a second support shaft. The second gear is meshed with the third gear, and the second gear and the third gear correspond to the second deceleration section.
The reaction force generating apparatus further comprises: a fourth gear which is integrally rotated with the third gear; and a fifth gear attached to the transmission member. The fourth gear is meshed with the fifth gear, and the fourth gear and the fifth gear correspond to the third deceleration section. The fifth gear is attached to the transmission member through a one-way clutch. The reaction force generating apparatus further comprises a return spring which applies a force in a rotation direction to the transmission member.
In the reaction force generating apparatus disclosed in International Publication No. 2013/099581, when a load applied to the pedal member is transmitted to the arm, the one-way clutch is engaged with the arm. For this reason, the torque of the rotating fifth gear is transmitted to the motor through the third to first deceleration sections. In contrast, a torque generated as a “reaction force” by the motor is transmitted to the arm through the first to third deceleration sections, and the reaction force in accordance with an operation force is applied to the pedal member.
When the load is released from the pedal member, the arm returns to its original position by the return spring. When the arm returns to its original position, the one-way clutch is released from the arm. For this reason, the torque of the arm is not transmitted to the motor.
International Publication No. 2013/099581 discloses a reaction force apparatus (reaction force pedal apparatus) which applies a reaction force against a stepping-on force to an accelerator pedal in accordance with the stepping-on force of the accelerator pedal. The reaction force apparatus comprises: a motor, a multistage deceleration mechanism for decelerating the rotation of the motor: and an arm which transmits an output of the multistage deceleration mechanism to the accelerator pedal.
When the driver steps on the accelerator pedal so as to pivot the accelerator pedal, the motor installed in the reaction force apparatus is designed to output a rotation force (torque) for pivoting the arm in an opposite direction. The torque outputted from the motor is transmitted to the arm through the multistage deceleration mechanism, and further transmitted to the accelerator pedal through the arm.
The above-mentioned multistage deceleration mechanism is a three-stage deceleration mechanism including: a first gear (input gear) meshed with a pinion gear fixed to the motor shaft; a second gear meshed with the first gear; and a third gear (output gear) meshed with the second gear. The first deceleration section is constituted by the pinion gear and the first gear, the second deceleration section is constituted by the first gear and the second gear, and the third deceleration section is constituted by the second gear and the third gear. The third gear serving as the output gear of the multistage deceleration mechanism is installed on a driving shaft having one end coupled with the arm.